MCP Scrcpy Vision

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses the return value (true/false) and the underlying method (dumpsys power/display), which adds useful context beyond basic functionality. However, it lacks details on permissions, rate limits, error conditions, or side effects, leaving behavioral gaps for a tool that likely requires device access.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences with zero waste: the first states the purpose and method, the second specifies the return values. It is front-loaded with the core functionality and efficiently structured, making every sentence earn its place without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's low complexity (1 parameter, no output schema, no annotations), the description is adequate but incomplete. It explains the return values and method, which is helpful, but misses parameter semantics and deeper behavioral context like error handling or prerequisites. For a simple status-check tool, it meets basic needs but could be more comprehensive.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 1 parameter with 0% description coverage, so the description must compensate. It does not mention the 'serial' parameter at all, failing to explain its purpose or format. However, since there is only one parameter, the baseline is higher, but the description adds no semantic value beyond the schema, resulting in a score just above minimum.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the specific action ('Checks if the device screen is currently on'), identifies the resource ('device screen'), and distinguishes it from siblings like android.screen.sleep, android.screen.unlock, and android.screen.wake by focusing on status checking rather than state manipulation. The verb 'checks' is precise and unambiguous.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage for determining screen state, but provides no explicit guidance on when to use this tool versus alternatives like android.screen.wake or android.screen.sleep. It mentions the method ('using dumpsys power/display'), which gives some context, but lacks clear when/when-not instructions or named alternatives for related scenarios.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.